Page 1 of 24

DOE Review Release 08/14/2015

Pantex External Coworker Model

ORAUT-OTIB-0086 Rev. 00

Effective Date: 08/07/2015

Supersedes: None

Subject Expert(s): Matthew H. Smith, Thomas R. LaBone, and Nancy Chalmers

Document Owner 

Approval: Signature on File

Matthew H. Smith, Document Owner

Approval Date: 08/05/2015

Concurrence: Signature on File

John M. Byrne, Objective 1 Manager

Concurrence Date: 08/06/2015

Concurrence: Signature on File

Edward F. Maher, Objective 3 Manager

Concurrence Date: 08/05/2015

Concurrence: Dianne Poncio Signature on File for

Kate Kimpan, Project Director

Concurrence Date: 08/05/2015

Approval: Signature on File

James W. Neton, Associate Director for Science

Approval Date: 08/07/2015

 

FOR DOCUMENTS MARKED AS A TOTAL REWRITE, REVISION, OR PAGE CHANGE, REPLACE THE PRIOR 

REVISION AND DISCARD / DESTROY ALL COPIES OF THE PRIOR REVISION.

New Total Rewrite Revision Page Change
Document No. ORAUT-OTIB-0086 Revision No. 00 Effective Date: 08/07/2015 Page 2 of 24

 

PUBLICATION RECORD

EFFECTIVE 

DATE

REVISION 

NUMBER DESCRIPTION

08/07/2015 00 Converted white paper to technical information bulletin. Incorporates 

formal internal and NIOSH review comments. Training required: As 

determined by the Objective Manager. Initiated by Matthew H. 

Smith.
Document No. ORAUT-OTIB-0086 Revision No. 00 Effective Date: 08/07/2015 Page 3 of 24

 

TABLE OF CONTENTS

SECTION TITLE PAGE

Acronyms and Abbreviations ............................................................................................................... 4

1.0 Introduction .............................................................................................................................. 5

1.1 Purpose........................................................................................................................ 5

1.2 Scope........................................................................................................................... 5

2.0 Background.............................................................................................................................. 5

3.0 General Approach.................................................................................................................... 6

4.0 Applications and Limitations..................................................................................................... 6

5.0 Coworker Data Development ................................................................................................... 7

5.1 1960 to 1977 ................................................................................................................ 7

5.2 1980 to 1993 ................................................................................................................ 7

5.3 1994 to 2010 ................................................................................................................ 8

6.0 Statistical Analysis ................................................................................................................... 8

7.0 Coworker Annual Dose Summaries ......................................................................................... 8

8.0 Attributions and Annotations .................................................................................................... 8

References ........................................................................................................................................ 11

ATTACHMENT A PANTEX EXTERNAL DOSE COWORKER STUDY INSTRUCTIONS 

(1960 to 2010)................................................................................................. 15

ATTACHMENT B PANTEX NTA FILM ISSUES AND DOSE ASSIGNMENTS FOR 

MONITORED WORKERS............................................................................... 20

LIST OF TABLES

TABLE TITLE PAGE

7-1 Annual Pantex external photon doses...................................................................................... 9

7-2 Annual Pantex external neutron doses................................................................................... 10

7-3 Annual Pantex external skin doses ........................................................................................ 11

A-1 Dosimeter types, periods of use, exchange frequencies, MRDs, and MDLs........................... 17

A-2 Sources of dose information................................................................................................... 18

A-3 Periods and MRDs for imputation models .............................................................................. 18

LIST OF FIGURES

FIGURE TITLE PAGE

B-1 Latent image fading of neutron film plotted as a function of time ............................................ 23
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ACRONYMS AND ABBREVIATIONS 

AP anterior-posterior

cm centimeters

DOE U.S. Department of Energy

DOELAP DOE Laboratory Accreditation Program

GM geometric mean

GSD geometric standard deviation

ICRP International Commission on Radiation Protection

in. inches

LOD limit of detection

keV kiloelectron-volt, 1,000 electron-volts

MCNP Monte Carlo n-particle

MDL minimum detectable level

MRD minimum recordable dose

mrem millirem

NIOSH National Institute for Occupational Safety and Health

NTA nuclear track emulsion, Type A

ORAU Oak Ridge Associated Universities

RDX Research Department Formula X

SC&A S. Cohen & Associates

SRDB Ref ID Site Research Database Reference Identification (number)

TBD technical basis document

TIB technical information bulletin

TLD thermoluminescent dosimeter

U.S.C. United States Code

WB whole body

β beta particle

λ gamma ray

§ section or sections
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1.0 INTRODUCTION

Technical information bulletins (TIBs) are not official determinations made by the National Institute for 

Occupational Safety and Health (NIOSH) but are rather general working documents that provide 

historical background information and guidance to assist in the preparation of dose reconstructions at 

particular sites or categories of sites. They will be revised in the event additional relevant information 

is obtained about the affected site(s). TIBs may be used to assist NIOSH staff in the completion of 

individual dose reconstructions.

In this document, the word “facility” is used as a general term for an area, building, or group of 

buildings that served a specific purpose at a site. It does not necessarily connote an “atomic weapons 

employer facility” or a “Department of Energy (DOE) facility” as defined in the Energy Employees 

Occupational Illness Compensation Program Act of 2000 [42 U.S.C. § 7384l(5) and (12)].

1.1 PURPOSE

This TIB provides information that allows dose reconstructors to base doses to Pantex Plant workers 

who have no or limited monitoring data on known site coworker data. In addition, the data in this TIB 

should be used to assign dose for gaps in the dosimetry record.

In cases where the monitoring records list a recorded “0,” that entry is assumed to mean that the 

dosimeter was issued and processed, and that no exposure or dose was detected in excess of the 

dosimeter LOD. In cases in which the records show that the worker was monitored for occupational 

external exposures, and one or more dosimeter exchange cycles are blank (or listed as a dash, slash, 

or hash mark), then the absence of an entry is assumed to indicate that the worker: 

1. Was not issued a dosimeter in that exchange cycle, or

2. That a dosimeter might have been issued but was not processed due to loss or damage, or

3. That the results of processing were incomplete or suspect and no dose was assigned because 

of the absence of processing or an errant result.

In such cases for years before 1988, NIOSH intends to apply (after consideration of the worker’s job 

title and the totality of the monitoring record), either (1) unmonitored dose based on external coworker 

data, (2) missed dose, or (3) ambient dose. After 1988, all personnel who entered the operational 

areas of the plant were required to wear a dosimeter as a condition for entry. The absence of a listed 

result, or the presence of a dash, slash, or hash mark for a given dosimeter exchange cycle in 1988 

and later years, should be interpreted to mean that the worker was not monitored because he or she 

was not present in the operational areas. Therefore, ambient dose should be assigned for those 

exchange cycles. 

1.2 SCOPE

Attributions and annotations, indicated by bracketed callouts and used to identify the source, 

justification, or clarification of the associated information, are presented in Section 8.0.

2.0 BACKGROUND

The Oak Ridge Associated Universities (ORAU) Team has prepared a series of coworker data studies 

to permit dose reconstructors to complete certain cases for which external or internal monitoring data 

are unavailable or incomplete. Cases that do not have complete monitoring data could fall into one of 

several categories:
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• The worker was unmonitored and, even by today’s standards, did not need to be monitored 

(e.g., a nonradiological worker).

• The worker was unmonitored but, by today’s standards, would have been monitored.

• The worker might have been monitored, but the data are not available to the dose 

reconstructor.

• Partial information is available, but it is insufficient to facilitate a dose reconstruction.

As described in ORAUT-OTIB-0020, some cases without complete monitoring data can be processed 

based on assumptions and methodologies that do not involve coworker data (ORAUT 2011). For 

example, many cases in the first category can be processed by the assignment of ambient external 

and internal doses based on information in the relevant site technical basis documents (TBDs).

Pantex used a variety of film and thermoluminescent dosimeter (TLD) dosimetry systems, as 

described in the latest revision of ORAUT-TKBS-0013-6, Pantex Plant – Occupational External Dose, 

(currently in the NIOSH comment resolution phase). In this TIB, see Attachment A, Pantex External 

Dose Coworker Study Instructions (1960 to 2010), for a description of these systems.

3.0 GENERAL APPROACH

External dose is measured with a dosimeter that indicates the dose that is received by an individual 

over a given length of time (e.g., a month or quarter). Multiple measurements over a year are 

summed to give the annual dose for the individual. Dosimeter readings below a given censoring level 

are reported as less than that level (usually referred to as the LOD). For example, the dose for a 

given month might be reported as <0.050 rem. These censored data are problematic for the 

development of coworker models. The previous approach to handling censored dosimeter readings 

(ORAUT 2011) was to substitute one-half of the censoring level for the censored results and then 

calculate the empirical 50th and 95th percentiles of the dataset. In statistics, this substitution is 

referred to as an imputation. In general, the imputation of a constant value like LOD/2 is not 

recommended (Helsel 2012) because it biases parameter estimates high. ORAUT-RPRT-0071, 

External Dose Coworker Methodology (ORAUT 2015b), outlines an alternative approach to analyzing 

the censored data that:

• Uses a lognormal probability model to generate a distribution of values to use for imputation 

rather than a constant one-half of the censoring level,

• Uses survival analysis techniques like those currently used for internal dose coworker 

modeling to estimate the parameters of a lognormal fit [i.e., the geometric mean (GM) and 

geometric standard deviation (GSD)] to the data rather than using the empirical 50th and 

95th percentile, and

• Uses multiple imputation to account for the uncertainty introduced into the parameter 

estimates by the imputation process.

4.0 Applications and Limitations

Some Pantex workers could have worked at one or more other major sites in the DOE complex during 

their employment histories. Therefore, the data in this TIB must be used with caution to ensure that, 

for likely noncompensable cases, unmonitored external doses from multiple site employments have 

been overestimated. This typically requires the availability of the recorded doses or TBDs or TIBs that 

cover external coworker dosimetry data for all relevant sites.
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The data in this document address penetrating gamma radiation, nonpenetrating dose, and neutron 

dose.

External onsite ambient dose should be applied as specified in the latest revision of ORAUT-PROC0060, Occupational On-Site Ambient Dose Reconstruction for DOE Sites. 

5.0 Coworker Data Development

Information for coworker analysis was found in two data sources provided by Pantex Plant staff 

(BWXT Pantex 2011, 2013). The former contains unadjusted Pantex dosimetry data for the period 

1960 to 2010, and the latter contains Pantex dosimetry data that were adjusted using an improved 

algorithm for the Panasonic 802 dosimetry system that was first introduced in 1980.

With respect to neutron dosimetry data, there are three general eras that were considered during the

analysis:

5.1 1960 TO 1977

During this period, nuclear track emulsion, Type A (NTA) film was used for neutron dosimetry. To 

address NTA film energy threshold under-response, angular dependence, and fading, a correction 

factor of 2.9 (see Attachment B, Pantex NTA Film Issues and Dose Assignments for Monitored and 

Unmonitored Workers) was applied to neutron data from BWXT Pantex (2011). No adjustments to 

photon or skin dose were needed. For 1978 and 1979, dosimetry data for neutrons, photons, and 

skin from BWXT Pantex (2011) were used with no corrections or adjustments.

5.2 1980 TO 1993

Starting in 1980, Pantex monitored personnel for external photon and neutron doses with the fourelement Panasonic 802 TLD dosimeter. In late 1992, the algorithm Pantex used to calculate doses 

was changed to resolve performance issues encountered during the 1989 Department of Energy 

Laboratory Accreditation Program (DOELAP) performance testing. This algorithm, called the 

“Stanford Algorithm,” was used to successfully pass DOELAP performance testing during 1993. The 

data that were recalculated using the Stanford Algorithm are contained in BWXT Pantex (2013). They 

are used in conjunction with the data in BWXT Pantex (2011) for the analyses during this period in 

this document. Specifically, due to data deficiencies noted by Pantex personnel (TLD data could only 

be recalculated for persons for whom the actual TLD element readings were available), the following 

data were discarded from each workbook (Prather 2015):

• Data that were present in BWXT Pantex (2011), but not present in BWXT Pantex (2013), and 

likewise, 

• Data that were present in BWXT Pantex (2013), but not present in BWXT Pantex (2011). 

In addition, for a given year and month for an individual, the highest whole-body (WB) skin dose, WB 

gamma dose, and WB neutron dose values were used, respectively, when comparing data (filtered as 

described above) in BWXT Pantex (2011, 2013). Finally, it should be noted that the neutron results 

using this improved algorithm are likely biased high because an unmoderated Cf-252 source was 

used for calibration rather than a moderated Cf-252 source that would have been more similar to 

Pantex workplace neutron spectra (Prather 2004).
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5.3 1994 TO 2010

In 1993, Pantex switched to the Panasonic 809/812 dosimetry system. This system passed DOELAP 

accreditation tests at that time, and no adjustments to dose are needed for the data in BWXT Pantex

(2011) for this period.

Additional information and assumptions about the development of these coworker datasets can be 

found in Attachment A, Pantex External Dose Coworker Study Instructions (1960 to 2010) of this TIB. 

6.0 Statistical Analysis

The data from BWXT Pantex (2011, 2013) were analyzed in accordance with the instructions in 

Attachment A and ORAUT-RPRT-0071 (ORAUT 2015b). The imputation model plots, fit with 

lognormal regression on order statistics, are included in ORAUT (2015c). Censored monthly badge 

readings were imputed from these lognormal imputation distributions, monthly doses were summed to 

compute annual doses, and yearly lognormal fits were made. After multiple imputations (K = 30), the 

parameters were averaged, resulting in the plots in ORAUT (2015c).

7.0 Coworker Annual Dose Summaries

The results of the analysis method described above are shown in Tables 7-1 to 7-3 for photon, 

neutron, and skin (nonpenetrating) dose, respectively. The tables also include the 95th percentile of 

the specified lognormal distribution and the number of workers in each year (N). These data should 

be used in the same manner as described in ORAUT-OTIB-0020 in relation to using either the GM 

(50th percentile) or the 95th-percentile value as a constant depending on the energy employee’s work 

history (ORAUT 2011). These doses should be assigned with energy ranges – and any applicable 

correction factors – as described in ORAUT-TKBS-0013-6, Pantex Plant – Occupational External 

Dose (ORAUT 2007). Note that there were an insufficient number of monitored workers for neutron 

and skin dose in the early years, so doses from 1960 to 1963 were combined to form multiyear 

coworker models.

8.0 ATTRIBUTIONS AND ANNOTATIONS

All information requiring identification was addressed via references integrated into the reference 

section of this document.
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Table 7-1. Annual Pantex external photon doses (rem). 

Year GM GSD 95th percentile N

1960 0.030 2.38 0.127 59

1961 0.040 2.77 0.211 61

1962 0.056 3.10 0.362 57

1963 0.018 4.79 0.240 217

1964 0.112 3.70 0.968 253

1965 0.037 4.31 0.406 416

1966 0.052 3.54 0.416 581

1967 0.057 3.62 0.471 562

1968 0.046 2.90 0.264 423

1969 0.042 3.22 0.289 432

1970 0.076 3.64 0.635 467

1971 0.070 4.05 0.700 495

1972 0.068 3.44 0.515 467

1973 0.125 2.43 0.537 441

1974 0.068 3.40 0.509 500

1975 0.039 2.99 0.237 493

1976 0.045 2.79 0.241 463

1977 0.080 2.15 0.281 465

1978 0.032 4.03 0.318 518

1979 0.087 2.81 0.478 714

1980 0.012 6.28 0.247 772

1981 0.072 4.63 0.900 908

1982 0.044 4.00 0.429 1,002

 1983 a 0.048 3.82 0.430 NA

1984 0.051 3.68 0.431 1,093

1985 0.043 3.95 0.415 1,172

1986 0.040 3.05 0.253 1,128

1987 0.027 2.83 0.147 1,160

1988 0.032 2.56 0.148 1,121

1989 0.023 3.13 0.151 1,437

1990 0.025 2.58 0.119 2,090

1991 0.027 2.40 0.115 2,126

1992 0.039 2.11 0.134 2,316

1993 0.020 2.27 0.077 2,633

1994 0.010 2.85 0.057 2,978

1995 0.010 2.78 0.056 3,107

1996 0.010 2.82 0.055 3,162

1997 0.009 2.65 0.043 3,000

1998 0.009 2.66 0.046 2,786

1999 0.010 2.57 0.045 2,686

2000 0.009 2.60 0.044 2,642

2001 0.009 2.53 0.042 2,770

2002 0.009 2.62 0.043 2,947

2003 0.009 2.46 0.040 2,996

2004 0.009 2.45 0.038 3,168

2005 0.009 2.44 0.039 3,210

2006 0.009 2.50 0.039 3,237

2007 0.008 2.73 0.040 3,183

2008 0.008 3.03 0.052 2,159

2009 0.009 2.95 0.054 2,110

2010 0.007 3.12 0.047 2,067

a. Per the instructions in Attachment A, the data for 1983 have been interpolated between the

1982 and 1984 values.
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Table 7-2. Annual Pantex external neutron doses (rem). 

Year GM GSD 95th percentile N

1960–1963 0.063 5.66 1.099 284

1964 0.049 4.33 0.542 249

1965 0.020 3.38 0.146 415

1966 0.027 2.63 0.133 581

1967 0.025 2.12 0.085 563

1968 0.026 1.81 0.069 423

1969 0.005 4.83 0.066 66

1970 0.022 1.96 0.066 465

1971 0.024 1.78 0.062 494

1972 0.026 1.67 0.060 464

1973 0.040 1.63 0.090 59

1974 0.052 3.99 0.508 29

1975 0.618 2.61 2.986 54

1976 0.004 4.62 0.044 463

1977 0.003 13.54 0.230 465

1978 0.003 11.51 0.155 518

1979 0.020 5.77 0.364 714

1980 0.003 5.71 0.058 772

1981 0.023 3.44 0.178 908

1982 0.024 3.41 0.182 1,002

1983 a 0.022 3.42 0.166 NA

1984 0.020 3.36 0.150 1,093

1985 0.025 4.01 0.241 1,172

1986 0.027 3.50 0.216 1,128

1987 0.019 2.84 0.105 1,160

1988 0.020 2.71 0.100 1,121

1989 0.016 3.10 0.101 1,437

1990 0.017 2.72 0.090 2,090

1991 0.019 2.49 0.084 2,126

1992 0.038 2.68 0.192 2,316

1993 0.033 2.51 0.151 2,633

1994 0.006 2.56 0.030 2,978

1995 0.006 2.56 0.030 3,107

1996 0.006 2.56 0.029 3,162

1997 0.006 2.45 0.024 3,000

1998 0.006 2.35 0.023 2,786

1999 0.006 2.28 0.022 2,686

2000 0.006 2.35 0.023 2,642

2001 0.006 2.35 0.023 2,770

2002 0.006 2.37 0.023 2,947

2003 0.006 2.25 0.021 2,996

2004 0.005 2.27 0.021 3,168

2005 0.006 2.22 0.021 3,210

2006 0.005 2.26 0.021 3,237

2007 0.005 2.45 0.021 3,183

2008 0.005 2.52 0.025 2,159

2009 0.005 2.36 0.022 2,110

2010 0.004 2.60 0.021 2,067

a. Per the instructions in Attachment A, the data for 1983 have been interpolated between the

1982 and 1984 values.
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Table 7-3. Annual Pantex external skin doses (rem). 

Year GM GSD 95th percentile N

1960–1963 0.011 3.72 0.100 230

1964 0.057 1.82 0.152 249

1965 0.037 2.67 0.186 414

1966 0.053 2.00 0.164 579

1967 0.055 1.97 0.168 559

1968 0.061 1.97 0.187 421

1969 0.059 1.79 0.155 393

1970 0.116 2.66 0.582 119

1971 0.139 3.20 0.942 97

1972 0.199 2.95 1.176 83

1973 0.028 3.58 0.231 409

1974 0.022 5.29 0.345 423

1975 0.016 2.78 0.084 483

1976 0.007 5.13 0.097 463

1977 0.008 5.44 0.134 466

1978 0.007 6.27 0.143 519

1979 0.021 4.01 0.207 714

1980 0.027 5.75 0.473 772

1981 0.131 4.71 1.675 908

1982 0.088 4.55 1.057 1,002

1983 a 0.097 4.16 1.013 NA

1984 0.106 3.83 0.968 1,093

1985 0.093 4.97 1.296 1,172

1986 0.100 4.22 1.072 1,128

1987 0.059 3.72 0.508 1,160

1988 0.061 3.32 0.435 1,121

1989 0.041 3.34 0.298 1,437

1990 0.040 2.39 0.169 2,090

1991 0.040 2.04 0.130 2,126

1992 0.023 3.46 0.179 2,316

1993 0.012 3.83 0.109 2,633

1994 0.012 2.98 0.072 2,978

1995 0.012 2.92 0.070 3,107

1996 0.012 3.00 0.072 3,162

1997 0.010 2.86 0.058 3,000

1998 0.011 2.84 0.061 2,786

1999 0.011 2.72 0.059 2,686

2000 0.011 2.77 0.058 2,642

2001 0.011 2.68 0.055 2,770

2002 0.011 2.75 0.056 2,947

2003 0.011 2.57 0.051 2,996

2004 0.010 2.57 0.049 3,168

2005 0.010 2.46 0.045 3,210

2006 0.010 2.56 0.048 3,237

2007 0.009 2.80 0.049 3,183

2008 0.010 3.20 0.069 2,159

2009 0.011 2.95 0.063 2,110

2010 0.008 3.21 0.058 2,067

a. Per the instructions in Attachment A, the data for 1983 have been interpolated between the

1982 and 1984 values.
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Wilson, R. H., 1987, Historical Review of Personnel Dosimetry Development and its Use in Radiation 

Protection Programs at Hanford, 1944 to the 1980s, PNL-6125, Battelle Memorial Institute, 

Pacific Northwest Laboratory, Richland, Washington, February. [SRDB Ref ID: 262]

Wilson, R. H., J. J. Fix, W. V. Baumgartner, and L. L. Nichols, 1990, Description and Evaluation of the 

Hanford Personnel Dosimeter Program from 1944 through 1989, PNL-7447, Battelle Memorial 

Institute, Pacific Northwest Laboratory, Richland, Washington, September. [SRDB Ref ID: 

4793]

Xu, X. G., W. D. Reece, and J. W. Poston, Sr., 1995, “A Study of the Angular Dependence Problem in 

Effective Dose Assessment,” Health Physics, volume 68, number 2, pp. 214–224.
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ATTACHMENT A 

PANTEX EXTERNAL DOSE COWORKER STUDY INSTRUCTIONS (1960 to 2010)

TABLE OF CONTENTS

SECTION TITLE PAGE

A.1 Data Sources ......................................................................................................................... 16

A.2 General Comments................................................................................................................ 16

A.3 Instructions ............................................................................................................................ 17

LIST OF TABLES

TABLE TITLE PAGE

A-1 Dosimeter types, periods of use, exchange frequencies, MRDs, and MDLs........................... 17

A-2 Sources of dose information................................................................................................... 18

A-3 Periods and MRDs for imputation models .............................................................................. 18
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ATTACHMENT A 

PANTEX EXTERNAL DOSE COWORKER STUDY INSTRUCTIONS (1960 to 2010) (continued)

A.1 DATA SOURCES

BWXT Pantex 2011 (Unadjusted Pantex Data)

Doses worksheet: Columns to be used: 

SSN (Column B), 

Year (Column G), 

Month (Column H), 

WB Skin (Column K), 

WB Gamma (Column L), and

WB Neutron (Column M).

BWXT Pantex 2013

Sheet1 worksheet: Columns to be used: 

Badge number (Column C), 

Year (Column A), 

Month (Column B), 

WB Skin (Column E), 

WB Gamma (Column F), and

WB Neutron (Column G).

A.2 GENERAL COMMENTS

• A blank cell means an individual was not monitored.

• A missing month means an individual was not monitored that month.

• A cell containing zero means the individual was monitored, but the result was below the 

recording limit. In this case, use the minimum recordable dose (MRD) values from Table A-1 

[from Table 6-2 of ORAUT-TKBS-0013-6 (ORAUT 2006)]. Proceed as follows:

– For 1963, use a neutron MRD of 15 mrem and MRD of 30 mrem for skin.

– For October 1964 to December 1972, use a neutron MRD of 20 mrem.

– For 1980, use a photon MRD of 20 mrem and MRD of 20 for skin.

– For time periods during which there were monthly and quarterly exchange periods, use 

the MRDs associated with the quarterly exchange period.

– For 1992 to 1993, use the Panasonic 802 MRDs.

– For 1994 to 2010, use the Panasonic 809/812 MRDs.

– For 1994 to 2010, use the quarterly neutron MRDs associated with moderated 252Cf 

neutrons.

• There are three eras at Pantex: the NTA era from 1960 to 1977, the Stanford era from 1980 to 

mid-1993, and the more recent era from mid-1993 to 2010.

• For 1978 and 1979, use the dosimetry data as they are recorded with no corrections or 

adjustments.

• During the NTA era, the adjustment factor for neutron dose is 2.9.

• For 1980 to 1983, use the Stanford algorithm data (BWXT Pantex 2013) and the unadjusted 

Pantex data (BWXT Pantex 2011) (see below).
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ATTACHMENT A 

PANTEX EXTERNAL DOSE COWORKER STUDY INSTRUCTIONS (1960 to 2010) (continued)

• For 1994 to 2010, use BWXT Pantex 2011. 

• For 1983, which has no available Stanford algorithm data, omit this year from the analysis. 

Dose reconstructors should interpolate between the 1982 and 1984 values. (Note: the data for 

1983 in Tables 7-1, 7-2, and 7-3 have been interpolated per these instructions). 

Table A-1. Dosimeter types, periods of use, exchange frequencies, MRDs, and MDLs (mrem) 

(derived from Table 6-2 of ORAUT 2007). 

Dosimeter type/ provider Period

Exchange 

frequencya

Skin

MRD

β/γ deep

MRD

Neutron

MRD

Skin

MDL

Deep

MDL

Neutron

MDL

βλ film/Tracerlab 01/1952–12/1959 Weekly 30b 10b None 40c 40c None

βγ film and NTA film/ 

Tracerlab

01/1960–03/1961 Weekly 30b 10b 15b 40c 40c None

04/1961–05/1963 Monthly 30b 10b 15b 40c 40c None

βγ film and NTA film/ 

Eberline

06/1963–09/1964 Monthly 10b 10b 10b 40c 40c None

βγ film and NTA film/ 

Landauer

10/1964–12/1968 2/month 40b 10b 10b,d 40c 40c None

βγ film and NTA film/ 

Landauer

01/1969–12/1972 Monthly 40b 10b 20b,e 40c 40c None

TLD 2-element/in-house 

and NTA film/Landauerf

01/1973–12/1975 Monthly 10 4 10b,d 30 30 None

TLD 6-element/in-house 01/1977–13/1979 Monthly 10 4 50 30 30 50

Panasonic 802/in-houseg 01/1980–12/1990 Monthly 20 20 50 30 30 50

Panasonic 802/in-houseg 01/1992–12/1999 Monthly 15 10 70 30 30 50

Panasonic 802/in-houseg 01/1992–12/1999 Quarterly 20 15 85 30 30 50

Panasonic 809/812/inhouseh01/1994–present Monthly 10 10 5i, 25j 30 30 50

Panasonic 809/812/inhouseh01/1994–present Quarterly 15 15 10i, 65j 30 30 50

a. Exchange frequencies were established from dosimetry reports. The initial weekly exchange frequency was changed to 

monthly in March 1961 (Tracerlab 1962–1963). A monthly exchange frequency continued with Eberline (Ashton 2003). An 

exchange frequency of twice per month for both beta/gamma and neutron films was established with Landauer in October 

1964; this frequency changed, for both beta/gamma and neutron films, to monthly in January 1969 (Adams 2003). NTA film 

provided by Landauer was used with the two-element TLD and exchanged monthly (Adams 2003).

b. Based on minimum doses recorded on dosimetry reports (Adams 2003; Ashton 2003; Tracerlab 1962–1963).

c. Estimated MDL typical of film dosimeter capabilities (Lalos 1989; NIOSH 1993; Wilson 1960, 1987; Wilson et al. 1990).

d. MRD for thermal neutrons (Adams 2003).

e. MRD for fast neutrons (greater than 1 MeV) (Adams 2003).

f. The Pantex in-house two-element TLD was implemented in 1973 for monitoring only beta/gamma radiation exposures. Use of 

NTA film continued for monitoring neutron exposures until the implementation of the six-element TLD system in 1977.

g. In 1992, the algorithms were changed for the Panasonic 802 to the Stanford algorithms (BWXT Pantex 2001). The dosimeter 

exchange frequency for nonradiation workers was changed from monthly to quarterly in 1992.

h. Beginning in January 1994, the Panasonic 809/812 dosimeter was provided to radiation workers and exchanged monthly. The 

Panasonic 802 dosimeter was provided to all other Pantex workers and exchanged quarterly. Between 1994 and 2000, 

Panasonic 802 dosimeters were gradually phased out and replaced by Panasonic 809/812 dosimeters for all workers.

i. DOELAP performance testing with moderated Cf-252 neutrons.

j. DOELAP performance testing with unmoderated Cf-252 neutrons.

A.3 INSTRUCTIONS

The following four data fields are required:

• The year in which the dosimeter was worn.

• The month in which the dosimeter was worn.
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ATTACHMENT A 

PANTEX EXTERNAL DOSE COWORKER STUDY INSTRUCTIONS (1960 to 2010) (continued)

• The identification (ID) number of the individual who wore the dosimeter. Social Security Number 

(SSN) is preferred over badge number. 

• The dose indicated by the dosimeter. NTA correction factor is 2.9 for 1960 to 1977. 

Table A-2 provides the sources of these data fields by period.

Table A-2. Sources of dose information.

Period Year Month Individual IDa Dosimeter Dose

1960–1979

and 

1994–2010

BWXT Pantex 2011, 

Column G

BWXT Pantex 2011, 

Column H

BWXT Pantex 2011, 

Column B

BWXT Pantex 2011, 

Column K, WB skin dose; 

Column L, WB gamma dose; 

and Column M, WB neutron doseb

1980–1993 BWXT Pantex 2013, 

Column A, and 

BWXT Pantex 2011, 

Column G

BWXT Pantex 2013, 

Column B, and 

BWXT Pantex 2011, 

Column H

BWXT Pantex 2013, 

Column C, and 

BWXT Pantex 2011, 

Column A

BWXT Pantex 2013, 

Column E, WB skin dose; 

Column F, WB gamma dose; and 

Column G, WB neutron dose 

as well as 

BWXT Pantex 2011, 

Column K, WB skin dose; 

Column L, WB gamma dose; and 

Column M, WB neutron dose

a. SSN is preferred over badge number. 

b. NTA correction factor is 2.9 for 1960 to 1977.

Due to data deficiencies noted by Pantex personnel (TLD data could only be recalculated for persons 

for whom the actual TLD element readings were available), the following data rows should be 

discarded from each workbook (Prather 2015):

• Data that is present in BWXT Pantex (2011), but not present in BWXT Pantex (2013), and

• Data that is present in BWXT Pantex (2013), but not present in BWXT Pantex (2011). 

For a given year and month for an individual, use the highest WB skin dose, WB gamma dose, and 

WB neutron dose values when comparing data (filtered as described above) in BWXT Pantex (2011, 

2013). 

Imputation models should be calculated using the periods in Table A-3, with MRDs (in mrem) derived 

using Section A.2 and Table A-1. 

Table A-3. Periods and MRDs (mrem) for imputation 

models.

Years Neutron Gamma Skin

1960–1963 15 10 30

1964–1972 20 10 40

1973–1976 10 4 10

1977–1979 50 4 10

1980–1991 50 20 20

1992–1993 85 15 20

1994–2010 10 15 15

Due to insufficient data for neutron and skin badge readings, combine 1960 to 1963 annual doses for 

coworker models (meaning there should be a coworker model for neutrons for 1960 to 1963 and a 
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ATTACHMENT A 

PANTEX EXTERNAL DOSE COWORKER STUDY INSTRUCTIONS (1960 to 2010) (continued)

coworker model for skin for 1960 to 1963). If a worker has more than one annual dose in the 1960 to 

1963 period, each of the annual doses should be included in the coworker model.
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ATTACHMENT B 

PANTEX NTA FILM ISSUES AND DOSE ASSIGNMENTS FOR MONITORED WORKERS

TABLE OF CONTENTS

SECTION TITLE PAGE

B.1 Introduction ............................................................................................................................ 21

B.2 Monitored Workers................................................................................................................. 21

B.3 Response to Thermal Neutrons.............................................................................................. 21

B.4 Angular Response of NTA Film.............................................................................................. 21

B.5 NTA Track Fading.................................................................................................................. 22

B.6 Conclusions ........................................................................................................................... 24

LIST OF FIGURES

FIGURES TITLE PAGE

B-1 Latent image fading of neutron film plotted as a function of time ............................................ 23
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ATTACHMENT B 

PANTEX NTA FILM ISSUES AND DOSE ASSIGNMENTS FOR MONITORED WORKERS 

(continued)

B.1 INTRODUCTION

This attachment summarizes the issues concerning NTA film in relation to the NIOSH proposal for 

evaluating neutron doses at Pantex. The effect of these issues on the proposed approach is 

discussed in detail sufficient to establish the appropriate method for interpreting neutron exposures for 

monitored personnel. The following issues are common to all sites that used NTA film:

• Dosimeter threshold response to thermal neutrons, 

• Methods used to correct for fading, 

• Energy dependence of fading characteristics, 

• Calibration sources and protocol, and

• Exchange or wear periods and wear conditions (temperature and humidity conditions). 

In addition, there are other uncertainty corrections.

B.2 MONITORED WORKERS

NIOSH recommends that measured doses for monitored workers be adjusted using a correction 

factor that includes corrections for the threshold energy of NTA film, the angular dependence of film, 

and for fading that occurs during the use of NTA film.

B.3 RESPONSE TO THERMAL NEUTRONS

NTA film has an effective threshold energy of about 500 keV. It is not sensitive to thermal neutrons 

and monitors only fast neutrons. The NIOSH recommendation recognizes this deficiency in NTA film 

and recommends a correction factor to adjust monitored doses. A Monte Carlo n-particle (MCNP) 

model was developed to determine the amount of dose that was missed due to a sensitivity threshold 

of 500 keV for the conditions likely to have been encountered by workers who received neutron doses 

at Pantex (LANL 2003). The model used Research Department Formula X (RDX) thicknesses of 0 to 

4 in., which is an appropriate approximation of the possible exposure scenarios. The results indicated 

that NTA film would miss 16% of the dose equivalent at the operator position (distance of 60 cm), 

which is the position likely to receive the highest dose. The MCNP evaluation also indicated that the 

NTA film would miss 29% of the dose equivalent at the observer position (distance of 240 cm), which 

would experience much lower doses by a factor of 16. Further distances could result in larger 

fractions of low-energy neutrons, but the corresponding dose rates would be much smaller due to the 

distance factor as well as the fact that low-energy neutrons are much less effective at delivering dose. 

The NIOSH recommendation selects the more conservative value from the observer position to be 

applied to all doses. The resulting correction factor is 1.4 versus a corresponding correction factor of 

1.2 for the operator position. This recommendation is favorable to claimants. 

B.4 ANGULAR RESPONSE OF NTA FILM

NIOSH recommends a factor of 1.33 to account for the angular response of NTA film. This factor is 

based on a study conducted by Kathren et al. (1965). Calibrations are typically done by irradiating the 

dosimeter to be calibrated in an anterior-posterior (AP) configuration. The AP configuration is used 

because that is the anticipated exposure configuration when a worker is wearing the badge on the

front portion of the body. The study was performed to determine the effect of irradiation at other 

angles by rotating the NTA film in front of a neutron source. This rotational movement resulted in AP, 
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ATTACHMENT B 

PANTEX NTA FILM ISSUES AND DOSE ASSIGNMENTS FOR MONITORED WORKERS 

(continued)

posterior-anterior, and lateral exposure; the results were the composite of exposure from all 

directions.

DOELAP requires the angular response of a dosimeter to be evaluated, but does not require that any 

angular dependence correction be made to measured exposures. A study of angular dependence 

problems (Xu et al. 1995), pointed out that exposures at some non-AP angles are less effective in 

delivering an effective dose equivalent because most of the important organs are in the anterior 

portion of the body. An AP exposure position delivers the highest effective dose equivalent. As a 

result, it is possible for exposures from isotropic dosimeters to overestimate the actual effective dose 

equivalent.

The correction factor recommended by NIOSH (1.33) is soundly based and favorable to claimants in 

that the dosimeter can in fact provide a reasonably accurate effective dose equivalent from an angular 

perspective because the exposure to neutrons normally occurs while working with the source of 

neutrons in front of the body. NIOSH is recommending an additional one-third be added to the 

monitored exposure.

B.5 NTA TRACK FADING

The NTA film issues at Pantex are essentially identical to the issues that have been raised and 

addressed at the Mound site. The fading issue was a major area of discussion in documented Mound 

calibration and fading experimentation on NTA film. The fading information from Mound is similar to 

that observed at other AEC sites that used NTA film.

In the July 28, 2010, transcript of the Mound Work Group meeting, the SC&A staff summarized the 

issues in relation to neutron fading. SC&A made the points that, in general, workers were exposed to 

moderated (shielded) neutron sources that lowered the average energy of the neutron spectrum in 

comparison with unshielded neutron sources. Lower-energy neutron tracks in NTA film fade faster 

than tracks from higher-energy neutrons, and even when the calibration source and exchange 

frequency were matched with the work conditions, the moderation might not have been well matched. 

As a result, SC&A suggested that the fading values used by NIOSH in the site profile (33% in the first 

week after exposure and 56% in the 2-week period) might not be favorable to the claimant. From the 

transcript it appears that all agreed that no worker at Mound would be exposed to a source that was 

exclusively composed of low-energy neutrons (below the NTA energy threshold), so there would 

always be some signal that could be registered by the NTA film.

On July 23, 2010, SC&A published a white paper, Sensitivity of NTA Film to Neutron Sources at 

Mound Laboratory, DRAFT Rev. 1 (SC&A 2010), which noted that NTA track fading was studied by 

the Mound staff in 1967 and 1968 and a formal Mound report was issued July 1, 1968, reporting that 

33% of the tracks faded after 1 week and 56% after 2 weeks. However, the purpose of that study was 

to establish the calibration and processing protocols that would appropriately compensate for the 

fading phenomena that was known to exist.

After the Work Group meeting, NIOSH found that the Mound experiments had also been published in 

the Health Physics journal (Kahle et al. 1969). The experimental description in this published peerreviewed report provides detail that might not have been clear in the initial reports. Twenty NTA film 

badges were exposed to a PuF4 source with an average energy of 1.3 MeV, and 20 badges were 

exposed to a moderated 238PuO2 source with an average energy of 0.9 MeV. Based on the 

unpublished Mound reports, NIOSH believes each badge contained four NTA films, which would be 
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ATTACHMENT B 

PANTEX NTA FILM ISSUES AND DOSE ASSIGNMENTS FOR MONITORED WORKERS 

(continued)

consistent with uncertainty data in the unpublished Mound reports. Each group of 20 badges was 

subdivided into two groups of 10. One group of 10 badges was exposed to the source each day for 

2 weeks, and one group was exposed on the day of development. The film badges were stored away 

from radiation before exposure, and during the interval from exposure to film development, at a 

constant temperature and constant relative humidity. Ordinary development and readout procedures 

were followed. Only those tracks that could be positively identified were counted. Mound reported:

Contrary to what was expected, the results indicated less fading of neutron tracks in films 

exposed to the lower average energy moderated 238Pu02 source. There was 33% fading 

of neutron tracks for film exposed to the PuF source for a seven day interval from 

exposure to film development and 56% fading for a fourteen day interval. There was 17% 

fading of neutron tracks for film exposed to the moderated 238Pu02 source for a seven 

day interval from exposure to film development and 30% fading for a fourteen day 

interval. These results are shown in Fig. 1. [Figure B-1]

Since more fading is expected for lower energy neutrons, the combined results of the 

two experiments indicate that latent image fading cannot be accurately predicted on the 

basis of average energy alone. The entire neutron spectrum must be considered to 

predict latent image fading of tracks in neutron monitoring film.

Figure B-1. Latent image fading of neutron film plotted as a function of time. 
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ATTACHMENT B 

PANTEX NTA FILM ISSUES AND DOSE ASSIGNMENTS FOR MONITORED WORKERS 

(continued)

NIOSH has recommended that a correction factor be applied to the neutron monitoring results to 

accommodate any fading that could have occurred during the wear period of the NTA film dosimeter. 

The correction factor is based on a value determined at Mound Laboratory of 9% per week for a 

4-week (1-month) period. Because fading corrections were incorporated into the processing protocol, 

the NIOSH recommendation to apply a fading correction of 1.56 is favorable to claimants. 

B.6 CONCLUSIONS

For monitored workers, the NIOSH recommendation is to apply a correction factor of 1.4 to correct for 

the threshold energy response of NTA film, a correction factor of 1.33 for angular dependence, and a 

correction factor of 1.56 to account for uncorrected fading of the NTA film. These correction factors 

produce the overall NIOSH correction factor (CF) of 2.9. Further, the final dose is modified by the 

International Commission on Radiation Protection (ICRP) Publication 60 correction factor of 1.91 

(ICRP 1991) (before January 1, 2010, when Publication 60 quality factors were implemented by 

Pantex dosimetry staff). In a paper by Vallario et al. (1969), the results of an intercomparison of AEC 

contractors and vendors were reported, with the observation that NTA film generally under-responded 

by 25% to 50%. This study was based on laboratory irradiations to known doses; no corrections were 

made for angular dependence. If the 50% under-response is corrected for angular response using 

the value above, the correction factor becomes 2.7, which is in reasonable agreement with the NIOSH 

recommendation. The NIOSH recommendation has a sound technical basis and should be 

implemented for monitored workers.